1. Field of the Invention
The present invention relates generally to improvements in methods for die attaching semiconductor devices to packages for the devices and, more particularly, to a new and improved method of die attaching a silicon-on-sapphire (SOS) semiconductor device to a package. The method provides a bond which maintains its mechanical integrity and heat conduction properties at relatively high temperatures.
2. Description of the Prior Art
It has been the common practice to use an organic resin such as an epoxy to attach an SOS device die to a support member for the die in a suitable device package. However, as application requirements have raised the temperature at which such devices and their attachment bond are required to operate, difficulties have been encountered. Organic resins tend to deteriorate at temperatures of about 200.degree. C and higher. Outgassing and bubbling occur in the bonding material, the mechanical integrity of the bond is jeopardized, and the heat conduction properties of the bonding material are impaired.
Such problems have not been as apparent in the case where the more conventional dice of silicon semiconductor devices are attached to package members through a layer of gold. As is well known, gold and silicon form an alloy useful for bonding silicon dice. However, gold has little or no adherent affinity for sapphire. The problems of SOS die attachment have been overcome by the present invention.